Exhibit 8-6
A sample of 75 information system managers had an average hourly income of $40.75 with a standard deviation of $7.00.
-Refer to Exhibit 8-6. The 95% confidence interval for the average hourly wage of all information system managers is
A)40.75 to 42.36
B)39.14 to 40.75
C)39.14 to 42.36
D)30 to 50

Question

Quizplus · Accepted Answer

We can use the formula for confidence interval: 
CI = X̄ ± z* (σ/√n) 
where 
X̄ = sample mean = $40.75 
σ = population standard deviation = $7.00 
n = sample size = 75 
z* = z-score for 95% confidence level = 1.96

Plugging in the values, we get: 
CI = $40.75 ± 1.96 * ($7.00 / √75) 
CI = $40.75 ± $1.81

Therefore, the 95% confidence interval for the average hourly wage of all information system managers is $39.14 to $42.36. Thus, the correct answer is C.

Exhibit 8-6 A Sample of 75 Information System Managers Had an Average